Apparatus for electroplating metal cylinders equipped with ports



Oct. 31, 1961 PENNINGTQN 3,006,837

APPARATUS FOR ELECTROPLATING METAL CYLINDERS EQUIPPED WITH PORTSOriginal Filed April 11. 1952 'INVENTOR. Harry Fennzngforz o W mm,

United States Patent 3,006,837 APPARATUS FOR ELECTROPLATING METALCYLINDERS EQUIPPED WITH PORTS Harry Pennington, 119 W. Summit Place, SanAntonio 12, Tex. Original application Apr. 11, 1952, Ser. No. 281,824.Divided and this application Nov. 2, 1954, Ser. No.

1 Claim. or. 204-280) This invention relates to apparatus forelectroplating metal cylinders equipped with ports; and it comprises incombination a metal cylinder, a wall of which is to be electroplated andwhich has ports intermediate its ends, and a plurality of port bleedersconstituting channelshaped elements of a corrosion-resistant metal, eachhaving a substantially flat section conforming in shape to the shape ofsaid ports, said port bleeders being removably secured in and serving toclose off said ports with the fiat sections depressed slightly below thewall of the cylinder which is to be plated, said port bleeders beingelectrically conductive, whereby when the cylinder is electroplated theyreceive a deposit of metal and the metal deposited on the cylinder wallis smoothly rounded over the edges of the ports; all as more fullyhereinafter set forth and as claimed.

This application is a division of my copending application Serial No.281,824, filed April 11, 1952, now abandoned and covers the portbleeders which are employed in the process of chromium plating which isdescribed and claimed in said application. In this prior application itis explained that the liners and cylinders of several types of internalcombustion engines have been chromium plated for many years withexcellent results. In the plating process the liner or cylinder isimmersed in a chromium plating bath and made the cathode. The anode isplaced inside the bore. Ring bleeders are placed at both ends of thebore to prevent the chromium deposit from building up and treeing on theinside surface. It is possible to chromium plate liners and cylinders inthis fashion to extremely close tolerances.

When it was attempted to extend this chromium plating process to theplating of the cylinders and liners of two-cycle engines of the dieseltype, for example, various difiiculties arose. These particular engineshave in their cylinders a ring of ports for scavenging air substantiallymidway between the ends of the bores. When an attempt was made tochromium plate these bores in conventional manner it was found that theplating built up not only around the edges of the ports but also on thebridges between the ports to such an extent that it was impossible toproduce chromium plated bores within the tolerances permitted. Areas ofthin deposit were produced and striations were formed in the plating.The same difficulties arose in the plating of free-piston cylinders andliners which have two sets of ports located a distance from the middleof the liner, which is equal to the piston strokes plus a distancerequired for pistons and rings to clear the ports, these ports admittingsupercharged air through one set and discharging exhaust gases throughthe other set. There are also diesel fuel injection nozzle holes locatedin the middle and lubricating oil holes through which lubricating oil isinjected into the liners. While the usual tolerances for the internaldiameters of such cylinders and liners are no greater than 2 to 3thousandths of an inch, the thickness of the chromium plating producedin conventional fashion in the annular belts including the port areasfrequently came to 0.01 inch or more above that outside this belt. It isnot feasible to hone a belt of this character to the required tolerance,since excessive honing would reduce the depth 3,006,837 Patented Oct.31, 1961 of lubricating oil channels in channel-type chromium andtherefore interfere with perfect lubrication locally.

Experience has shown that the heavy deposits of chromium on the edges ofthe ports and on the bridges between the ports which are caused by theconventional chromium plating of cylinders and liners havingintermediate ports, are struck by the piston rings and that this causessuflicient damage either to the deposits, to the rings and/or to thepistons to disable the engines or seriously to shorten their lives.

In the chromium plating of the bores of cylinders and liners of internalcombustion engines the bores are usually held vertically in the platingbath usually with the head end up. When these bores are provided withintermediate ports, as in the case of two-cycle and freepiston engines,it has been found that the openings cause turbulence of the bath justabove the ports. This turbulence results in thinner than normal chromiumand it causes striations to be formed in the chromium plating. Thesestriations are vertical and usually cannot be removed completely byhoning. These striations and thin chromium areas bridge the piston ringsin the high pressure areas preventing the piston rings from making atight seal with the Walls of the bore and thus causing loss of power dueto gas blow-by past the rings.

As described in my acknowledged copending application I discovered asimple way of overcoming the described diiiiculties involved in theplating of cylinders and liners which have ports intermediate theirlength. This involves inserting prior to the chromium plating proceduremy novel port bleeders in the ports of the cylinders or liners withtheir substantially flat faces slightly depressed beneath the surface tobe plated. The flat metal surfaces of these bleeders receive thechromium deposit which otherwise would build up on the edges of theports. If inserted flush with the surface to be plated and then removedafter the plating operation sharp edges are left around the ports. But Idiscovered that, if the bleeders are inserted with their flat surfacesslightly below the surface to be plated the chromium forms a smoothlyrounded deposit covering the edges of the ports. The inside edges ofthese ports are usually chamfered and when these are plated, using mynew bleeders, the chromium follows the chamfered edges leaving no sharpedges at the liner Wall. The chromium is deposited in uniform thicknessthroughout the bores and Well within the tolerances permitted.Striations and thin areas of deposit are eliminated. This enablesretention of a continuously tight operating seal between the pistonrings and the wall of the bore thus sustaining engine power.

My invention can be described in greater detail by reference to theaccompanying drawing which shows, more or less diagrammatically, twoembodiments of my port bleeder. In this showing,

FIG. 1 is a perspective view of one of my port bleeders of simple type,

FIG. 2 is a partial view in elevation of the inside surface of acylinder showing a scavenging port with one of my bleeders insertedtherein,

FIG. 3 is a partial transverse sectional view of a liner showing a portfitted with the bleeder of FIG. 1, the section being taken along theline 33 of FIG. 2.

FIG. 4 is a perspective view of a tool which can be used to insert fromthe inside the bleeder of FIG. 1 to a predetermined distance below theinner surface of the bore of a liner or cylinder.

FIG. 5 is a perspective view of a modified form of port bleeder adaptedto be inserted in the port of a liner from the outside to apredetermined depth,

FIG. 6 is a partial transverse section taken through directly from sheetmetal using a simple die punching and forming operation. FIG. 7 showsthe blank cut from sheet metal. The bleeder has a substantially flatcentral section 2 and two wings or spaced-parallel flanges 3 at rightangles to the flat section. The flanges are narrower than the fiatsections of the bleeders, being cut away at points 13 where the flangesjoin the fiat sections. The outer edges of the flanges are beveled as at14.

This assists in inserting the bleeders into the ports.

Thus, if the end of a bleeder is inserted in a port and then twisted sothat its flanges enter the port, the walls of the port assist incompressing the flanges together.

The beveled edges also assist in centering the bleeders in the ports.The contour of the flat section of the bleeder conforms to the shape ofthe port in which the bleeder is to be inserted, being usuallyrectangular with rounded corners, as seen clearly from FIG. 2. Theoperating face 4 of the bleeder receives a chromium deposit and thisface is depressed slightly below the surface of the, bore, as shown bestin FIG. 3 where the liner is shown at 5 and a port at 6. The bleedersare made of a resilient metal, such as steel, and the flanges are bentapart at their outer ends so they diverge slightly. The

flanges press against the side Walls of the port and have sufficientresilience to hold the bleeders firmly in position once they are set. Iprefer to make them from stainless sheet metal having a thickness ofapproximately 0.025 inch.

The bleeders of FIG. 1 can be set a predetermined distance below thesurface of the bore by the simple tool shown in FIG. 4. This consists ofa block 7 of wood or the like whose face 8 is advantageously arcuate toconform in shape to the bore of the cylinder or liner. The face of theblock is provided with a raised section 9 which may be rectangular plateof metal secured to the block and this raised section is alsoadvantageously provided with a curved face to conform to the curvatureof the bore. The height of the raised section of the block correspondsto the depth to which the bleeder is to be inserted in the bore of thecylinder or liner. The dimensions of the raised section are somewhatsmaller than those of the port. A handle 10 can be provided at the rearof the tool. In use the bleeder is inserted part way into a port and theraised section of the tool is then pressed against the face of thebleeder until the raised section seats in the port and the face of theblock becomes flush with the'face of the bore. The bleeder is thusdepressed beneath the surface of the bore-a distance correspondingexactly to the thickness of the raised section of the tool.

When in position in the ports of a liner or cylinder my bleeders shouldbe depressed below the surface of the bore a distance substantiallycorresponding to the depth i.e. the radius of the chamfer 11. When thus5 positioned the chromium deposit is smoothly rounded over the edges ofthe bores. V 7

=In- FIGS. 5 and.6 a modified port bleeder is shown generally at 1a.;This bleeder is provided with spaced parallel flanges 3a whose outerends terminate in diverging right-angle end flanges 12 which lie in aplane parallel to that 'of the fiat section of the bleeder. bleeder isinserted into the ports of the 'liner from the outside. The flanges 3ahave a length which corresponds to the depth of the ports minus thedistance to which the bleeders are depressed beneath the bore of theliner. 'Whenv these bleeders are forced into the ports the divergingflanges serve as means for preventing fur- This ther insertion of thebleeders when they reach their predetermined positions in the ports.

In the plating process making use of my port bleeders a free-piston or atwo-cycle engine liner, for example, which has been prepared ready forplating is equipped with ring bleeders at both ends of the bore and myport bleeders are inserted in each of the ports to the correct depth.The so-equipped article is then introduced into a chromium orotherplating bath below the surface of the bath. A suitable cylindricalanode is positioned axially in the bore with proper clearance and theplating operation is then conducted in conventional manner. Afterplating the plated liner is removed from the bath and the bleeders areremoved from the ports. The plated bore is then usually honed inconventional fashion. In many tests I have found it possible to chromeliners haying ports to a predetermined diameter with a tolerance of only0.0005 inch throughout.

The port bleeders can be used twice and then stripped by inserting themin the ports of a worn liner while the chrome plate of the latter isbeing stripped. A double thickness of chrome plate on the bleeders isreadily re moved during the conventional stripping operation and thenthe bleeders are suitable for reuse.

While I have described what I consider to be the most advantageousembodiments of my invention it is evident of course that variousmodifications can be made in the specific structures of my bleederswhich have been described without departing from the purview of thisinention. Thus it would be possible to employ bleeders having fourspring flanges instead of two although the two flanges which have beendescribed are adequate to hold the bleeders in position during thechromium plating. When two flanges are employed it is a simple matter topress the flanges together with the fingers when the bleeders are beinginserted in a port while this could not be done readily with fourflanges. It is evident that my bleeders can be used in the electroplating of the surfaces of 'all types of metal elements of cylindricalshape which have ports of any type intermediate their ends. Thus mybleeders canrbe used in diesel fuel injection nozzle holes, inlubricating oil holes, in all the ports of the cylinders and liners offree piston engines etc. with the result of successfully eliminatinghigh chromium on and adjacent the edges of all these openings, andelimination of striations and low-chromium areas in the deposits abovethe holes when plated vertically. They are, of course, particularlyuseful inplating such surfaces from plating baths which have lowthrowing power. Metals other than chromium, such as nickel and cadmium,can be deposited with advantage making use of my bleeders in operationsrequiring such use. While the particular metal used in making mybleeders is not important it is advantageous to employ a metal which iscorrosion resistant as well as being resilient. Bronze can be used insome cases. It is possible, of course, to plate the bleeders with acorrosion resistant metal in order to prolong their life. The bleedersmust obviously be electrically conducting in order to perform theirfunction. In the case of plating articles having large openings it isadvantageous to have the metal-receiving faces of the bleeders conformin curvature to the curvature of the surfaces which are being plated.The bleeders can be used in the plating of either the outside or theinside surfaces of cylinders or the like. Further modifications of. mybleeder which fall within the scope of the following claim will beimmediately evident to those skilled in this art.

What I claim is: V

A combination of units especially adapted for electroplating operationswhich comprises:

(a) a metallic cylindrical wall liner structure for internal combustionengines having at least one port intermediate its ends,

(12) a port bleeder located in each of said ports,

(e) each of said port bleeders being channel-shaped,

(d) each of said port bleeders having a substantially fiat centralsection conforming in shape to the shape of the ports of said cylinder,

(e) each of said port bleeders having spaced parallel flanges onopposite sides of said flat section whose outer ends diverge slightlyand which press against the side walls of said ports so as to hold thebleeders resiliently in position during the plating operation,

(1) each of said port bleeders serving to close 011 the port it islocated in,

(g) each of said port bleeders having its said flat section depressedslightly below the interior surface of said metallic cylindrical wallstructure,

(h) said port bleeders being electrically conductive so that when thesaid wall structure is plated, the port bleeders receive a deposit ofmetal and the metal deposited on the cylinder is smoothly rounded overthe edges of the ports.

References Cited in the file of this patent UNITED STATES PATENTS825,332 Mack July 10, 1906 1,224,762 McKeown May 1, 1917 1,861,446 MaagJune 7, 1932 2,048,578 Van Der Horst July 21, 1936 2,367,159 Van DerHorst Jan. 9, 1945 2,574,417 Rowe Nov. 6, 1951

